1. Field of the Invention
The present invention relates to a novel organic electroluminescence device and a novel compound having an aluminum complex structure used in the device, and more particularly, to an organic electroluminescence device having excellent properties of high luminance, high efficiency of light emission and long life and a compound having an aluminum complex structure which provides the device with the excellent properties by using it as a component of the device.
2. Description of Related Art
Investigations to increase efficiency of light emission by forming an electron injecting and transporting layer in an electroluminescence device (hereinafter referred to as an EL device) have heretofore been made. The investigations revealed drawbacks that formation of an exciplex is observed and that life time of light emission, is short even though light emission of high luminance can be obtained. The investigations also revealed other drawbacks that cleavage between a metal electrode and an organic layer occurs after a voltage is loaded for a long time and that an organic layer or an electrode turns turbid by crystallization and luminance of the emitted light is decreased. Therefore, it has been required that occurrences of these phenomena are prevented.
As an example of a compound having a specific aluminum complex structure which is comprised in an organic EL device as a component thereof, compounds disclosed in U.S. Pat. Nos. 5,141,671 (1992) and 5,150,006 (1992) can be mentioned. These compounds are used as a material for a light emitting layer emitting blue light with doping of a polycyclic aromatic compound.
However, an aluminum-quinoline complex is used additionally as an electron injecting and transporting layer in these inventions and a drawback is found that efficiency of light emission is low when the device does not contain an electron injecting and transporting layer.
An organic EL device using a specific aluminum complex is disclosed in European Patent Application Laid-Open No. 579151A2. However, this aluminum complex is different from the compound having an aluminum complex structure disclosed in the present invention.